>perl -wMstrict -le
"$_ = 'x77x888x1x';
 ;;
 'zonk' =~ m{(\w+)}xms;
 ;;
 print 'before: $1 is ', defined($1) ? qq{'$1'} : 'undefined';
 print X1();
 print 'after: $1 is ', defined($1) ? qq{'$1'} : 'undefined';
 ;;
 sub X1 { s/(\d+)//;  print qq{  '$1'};  return $1 + X2(); }
 sub X2 { s/(\d+)//;  print qq{  '$1'};  return $1 + X3(); }
 sub X3 { s/(\d+)//;  print qq{  '$1'};  return $1;        }
"
before: $1 is 'zonk'
  '77'
  '888'
  '1'
966
after: $1 is 'zonk'